G-Works Gas Saver: Canister Fuel Transfer Adapter Review

Is your Gear Closet Full of Partially Used Isobutane/Propane Gas Canisters?

If you use a canister backpacking stove like a Jetboil Flash or an MSR Pocket Rocket, you probably have a lot of partially used isobutane canisters in your gear closet. While the ease of using canister gas stoves has revolutionized backcountry cooking, it also creates a lot of waste since there’s no convenient way to use up all the leftover gas in a canister or to combine two partially filled canisters to make a whole one.

The G-Works Gas Saver lets you transfer the contents of one gas canister to another.

That’s why the G-Works Gas Saver caught my eye. It’s a two-way isobutane canister adapter that lets you transfer the gas from one isobutane canister to another so you can refill partially used or empty canisters.

Made in Korea, you can buy the G-Works Gas Saver on Amazon. Be forewarned: it doesn’t come with any instructions at all, which is a little concerning since it’s used to transfer highly flammable materials that can cause serious injury or burn down your house (see disclaimer below). And while the G-Works Gas saver does make it possible to transfer gas between canisters, I suggest you use an inverted canister stove like the Kovea Spider or the Jetboil Joule, not an upright one, to burn gas that’s been transferred to another canister. More on this below.

How It Works

The G-Works Gas Saver plugs into gas canisters using what called a Lindal valve. This is a standard canister attachment system that is used universally on canister stoves (in the US, but not Europe) to ensure that canisters from different manufacturers can interoperate with other manufacturers’ stoves. For example, it’s the reason you can use Jetboil, MSR, or Primus isobutane fuel canisters with a Snow Peak canister stove.

The G-Works Gas Saver has two Lindal valves that you screw onto the canisters and a twist valve that controls the flow of gas from one canister to another. When transferring gas, you want to have it flow from the higher pressure canister to the lower pressure canister. One way to achieve this is to stack a fairly full canister over an empty canister (the full canister is under higher pressure than the empty one), so the fuel drains to the lower canister.

This canister had an empty weight of 90 grams and a final weight of 200 grams, so 110 grams of fuel were transferred.

You can also raise the pressure inside the upper canister, by raising its temperature. For example, plunge the upper canister into a bowl of hot water for a few minutes before attaching it to the Gas Saver. This is useful to speed things up and when the bottom canister has more gas in it than an upper, mostly drained canister. The actual speed of the transfer depends on the amount of the pressure gradient, but figure about 15-20 minutes to fill a small empty canister from a large, mostly full canister. The process is not terribly fast.

While can overfill the bottom canister beyond the amount of fuel that it originally held, I’d advise against doing this for safety reasons. You can measure the amount of fuel transferred by weighing the canister before and during the process so you know when to stop.

For example, if you know you have an empty canister, search for its net weight, which is usually printed on canister’s exterior. If a canister has a net weight of 110 grams, this tells you it had 110 grams of fuel in it when you bought it new. When refilling it, stop when its empty weight has increased by 110 grams. It helps to have a scale handy for this process.

You can increase the pressure inside a canister by plunging it into hot water.

What Gets Transferred?

Good question. It’s hard to know exactly what kind of gas is being transferred from one canister to another since different canister manufacturers mix butane, isobutane, and propane in different combinations to improve cold weather performance. Things get even more uncertain when you mix one manufacturers fuel into another. Do the constituent components stay “mixed” or do they separate when transferred using gravity. For example, would the heaviest fuel component drain from the top canister into the bottom canister first before the lighter components?

What I’ve found by burning the transferred gas on different stove types is that I get 15-20 minutes of burn time when using an upright canister stove, after which the force of the flame weakens considerably or putters out completely, even though there is plenty of liquid fuel left in the recharged canister. This happens even after I’ve let the canister rewarm to outside air temperature between long burns, but the flame never returns to full power in an upright stove after it begins to falter.

But if I invert the recharged canister and plug it into an inverted canister stove, like the Kovea Spider, which burns unvaporized liquid fuel, I can get another 20-30 minutes of burn time from the canister until it’s completely empty.

I’ve seen this happen before with canister stoves, when the fuel component inside the canister that is responsible for vaporization in an upright stove burns off (propane) leaving the liquid component (isobutane) behind. Hik’in Jim (Adventures in Stoving) has an excellent article that explains canister gas blends, vaporization, and cold weather performance that it worth reading if you want to dig into the details.

Use with Inverted Canister Stoves

Based on my testing, my advice would be to only use an inverted canister stove with refilled canisters to ensure that you can use all of the gas in the canister. The Kovea Spider can burn fuel from a canister oriented in either direction. I think inverted canister stoves like it are the best way to ensure you can use the entire canister contents when camping with refilled fuel canisters.

The Kovea Spider stove can burn liquid fuel from a canister that’s been turned upside down.

Is the G Works Gas Saver worth buying? While it provides a way to transfer unused gas between canisters, it takes a fair amount of time and fiddling to get the job done. I honestly can’t see this becoming a big consumer hit and I doubt any of the existing canister or stove manufacturers will champion it, though time will tell. While the G Works Gas saver does reduce canister waste, there are easier ways to accomplish this by switching to another backpacking fuel source such as alcohol, white gas, wood, or esbit cubes, which are unencumbered by fixed size containers.

Disclaimer: SectionHiker.com is not responsible for any bodily harm or damages resulting from the use of information in this article. The author purchased this product with his own funds.

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27 comments

I sometimes refill small propane tanks from a large bulk tank. When I do that, I’ll put the small tank in the freezer for about a half hour to lower the pressure in that tank prior to filling it. Is doing that, along with putting your donor tank in hot water, a useful technique for using the G Works Gas Saver?

I love my JetBoil, but I’m getting less and less enthused with upright canister stoves for cold weather use.

Great article. I buy the 440g Coleman canisters in WalMart for 8 bucks. This gizmo has paid for itself in less than one season! I weigh the bottom canister every 30 seconds, they fill up fast when the large one is at or near full pressure, around 2 minutes. I’m wondering what upright stove you’ve been using where you experience the pressure drop? I’ve been using the refilled canisters with my MSR Windboiler in temps above freezing and have not experienced this.

Sounds like you’re refilling your canisters with from larger unused canisters from Walmart. I’m using ones that are only partially full after being used in trips, so that some or most of the vaporizing element has probably burned off. That’s my point, really. You don’t know what’s in a used canister, so hedge your bets and bring an inverted style stove than can burn the fuel in gas or liquid form, if necessary.

You don’t need to buy a Crunchit if you have a swiss army knife or a multitool. Hook the can opener over the bottom rim of the canister and easily punch a hole in the side of it. An old fashioned can tapper would work too, but I haven’t seen one of those in awhile.

In my case, I put the empty bottom canister in the refrigerator for a few minutes to let it cool, take it out and then refill it. I wonder if it’s similar to your method of plunging the upper canister in hot water.

I made a ‘transfer adapter’ myself. I use it mainly fot refilling the small 100gram cannisters. Works great. After refilling it a couple of times, I throw it away for safety. I am waiting for an ultralight adapter for the Europeing CampingGaz cartridges. The one I use now is twice the weight = 50 grams of my lightest burner = 25 grams. Bit out of balance… Anyone a suggestion?

What it the point. You’re left with a partially full canister at lower pressure. Invent a device that (without a lot of heat) will increase pressure in the almost empty canister to top off other canisters. Now you would have something I would buy.

For those interested, the main thing with canister stoves is the BOILING POINT of the liquid that is in the canister. For the common “gasses” used in backpacking stoves, the boiling points are:

Propane -44°F (-42°C) Isobutene 11°F (?11 °C) Butane 31°F (-1°C)

Propane will boil to a gas at temps as low as -44°F, but butane is good only down to 31°F. In freezing temps, a canister will burn off the propane and isobutene first and the butane just sits in the canister as a liquid. Many Boy Scout troops see this in winter camping when using the two burner “Colman” type stoves with the green fuel bottles and the stove stops working because the valve froze up. Well it didn’t freeze up, the propane is just been burnt off. Use a propane tank from a home grill and the stove will work all day, and night, long till the propane tank is empty.

As to why a mix of fuels is used, it is cost – butane and isobutane are cheaper than propane.

As to why the inverted canister stoves will work at colder temps as the liquid fuel flows into the stove at outside pressure and is ignited. This process uses the fuels FLASH POINT temps, or the temp that a fuel will burn at once it is ignited, like with a match. Which are:

Propane -155°F (-104°C) Isobutene -117°F (?83°C) Butane -76°F (?60°C)

So, as long as you are not below -76°F, any canister should work with an inverted stove.

I’m confused. Why do people end up with several partially-filled canisters? When I return from a trip, I weigh the unfinished canister to determine how much net fuel is left inside (in ounces) and mark it on the bottom with a sharpie. Since I know approximately how much fuel I use per day, it is easy to estimate how many camping days a partial canister will last. When departing on the next trip, if there is any doubt that the fuel left in the partial canister will be enough, I pack a second full one. I use all canisters until they are empty. While it is true that a partial canister may refuse to burn in very low temps because the liquid butane inside will not “boil”, I have never encountered a canister that would not feed fuel to my upright MSR pocket rocket stove at temps above 40*F. If this is indeed a problem for certain brands of fuel, I would like to know which ones so I can avoid them.

Well, I think the idea is to save the weight and space of a 2nd canister. Yea, I know. It’s just another 5 ounces. But this never ending weight reduction strategy pays off when you’re tired, hungry and deadbeat hiking up hill at the end of the day. Your idea of weighing and marking return canisters is a good one. My low canisters end up in the car camping kitchen box. A hot cup of coffee at the departing trail head is a must in old age.

I intentionally overfilled an existing canister by about half to three quarter ounce, thinking I could get a bit more usage out of it. As I was driving to the trailhead, at about7k feet in elevation the canister began venting. It stopped venting on its own, apparently when the internal pressure was within limits, because I was still able to use it fourthe two day trip.

I know this is an old thread but thanks for all the comments. I went and bought one of these devices really to consolidate my fuels. It works great. I had about 10 partially used fuel cans from various backpacking trips with scouts. I only take full canisters on trips. By consolidating the partially used canisters I know I always have full cans at the start of every trip. Because of the concern of not being able to burn off if it’s too cold, I have a small adapter tube that allows me to use my canisters an upside-down for the liquid fuel. It works great. I’ve never had to use it but tested it out to make sure it works.